I am sure that if you google it, you’ll find some sort of guide. It’s not very complicated, really…

You have a unique BTC address. You convert any currency to Bitcoins, then deposit the Bitcoins using your unique BTC address that you got when you made a wallet. If you want to make purchases somewhere, they’ll provide you with a BTC address to send the money to. Send the specified amount of money to that address from your BTC address. It will then go through the Blockchain process where transaction confirmations happen. Depending, after about 3-5 confirmations, which should take about 30min depending on the priority of the transaction. Once the other address received the money, you’ll receive what you purchased.

Please also note that on some websites you’ll be given a deposit BTC address. You just send the amount of BTC to that Bitcoin address, and you’ll receive funds (bitcoins) to easier make purchases on that website. Some wallets are more secure than others. There are online wallets, which are easier to use.